This is how the email should look in your inbox

When you click to open email this is what it will look like

At the bottom of the page click "pay invoice"

On the menu bar on the left side click "invoices" to view your invoices

select the invoice you want to pay

to pay click the button on bottom to pay

Add your credit card information. You may choose the keep the card on file, you do not have to

If you have a card on file but want to use a different card this is how you would add it